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  • JTextArea thread safe?

    - by Dhaivat Pandya
    Hello everyone, I have some code that does some initialization (including making a JTextArea object), starts three seperate threads, and then these threads try to update the JTextArea (i.e. append() to it), but its not working at all. Nothing shows up on the JTextArea (however, during the initialzation, I print some test lines onto it, and that works fine). What's going on? How can I fix this? Also, each of those threads sleeps a random amount of time every time it has to update the JTextArea. Sorry I haven't provided any code, its all spread out over several files.

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  • How can I improve the performance of this double-for print?

    - by Florenc
    I have the following static method that prints the data imported from a 40.000 lines .xls spreadsheet. Now, it takes about 27 seconds to print the data in the console and the memory consumption is huge. import org.apache.poi.hssf.usermodel.*; import org.apache.poi.ss.usermodel.*; public static void printSheetData(List<List<HSSFCell>> sheetData) { for (int i = 0; i < sheetData.size(); i++) { List<HSSFCell> list = (List<HSSFCell>) sheetData.get(i); for (int j = 0; j < list.size(); j++) { HSSFCell cell = (HSSFCell) list.get(j); System.out.print(cell.toString()); if (j < list.size() - 1) { System.out.print(", "); } } System.out.println(""); } } Disclaimer: I know, I know large data belong to a database, don't print output in the console, premature optimization is the root of all evils...

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  • garbage collector Issue

    - by Eslam
    this question is like my previous one Given: 3. interface Animal { void makeNoise(); } 4. class Horse implements Animal { 5. Long weight = 1200L; 6. public void makeNoise() { System.out.println("whinny"); } 7. } 8. public class Icelandic extends Horse { 9. public void makeNoise() { System.out.println("vinny"); } 10. public static void main(String[] args) { 11. Icelandic i1 = new Icelandic(); 12. Icelandic i2 = new Icelandic(); 13. Icelandic i3 = new Icelandic(); 14. i3 = i1; i1 = i2; i2 = null; i3 = i1; 15. } 16. } When line 14 is reached, how many objects are eligible for the garbage collector? A. 0 B. 1 C. 2 D. 3 E. 4 F. 6 i choosed A but the right answer is E, but i don't know Why?

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  • HibernateFilter.doFilter ServletException?

    - by Austin R
    I have pretty much zero experience setting up servers, but currently my job is to set one up (don't ask why). It's an an apache-tomcat6 server. I followed some instructions step by step, and when it came time to test that everything was working, here's what I got: I know this is a bit of a shot in the dark, but does anyone know what I can do to fix this? Please let me know if there's any further information I can provide to help!

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  • What is a right way to use servlets?

    - by vikp
    Hi, I'm studying EJB3. I have a session bean which provides services to create/update customer accounts. This session bean offers services on the lines of: public void addCustomer(Customer c); public void updateCustomer(Customer c); Ideally I'd like to have a single servlet: CustomerServlet and it would invoke the session beans that I have listed above. Problem is that I have two JSPs: UpdateAccount.jsp and CreateAccount.jsp. Both of these JSPs have a form with a method POST and action "CustomerServlet". How can I distinguish in a customer servlet which operation I should carry out: createAccount or updateAccount? I guess the alternative is to have a separate servlet for each operation... Thank you

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  • Hibernate: same generated value in two properties

    - by Markos Fragkakis
    Hi, I have an entity A with fields: aId (the system id) bId I want the first to be generated: @Id @Column(name = "PRODUCT_ID", unique = true, nullable = false, precision = 12, scale = 0) @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "PROD_GEN") @BusinessKey public Long getAId() { return this.aId; } I want the bId to be initially exactly as the aId. One approach is to insert the entity, then get the aId generated by the DB (2nd query) and then update the entity, setting the bId to be equal to aId (3rd query). Is there a way to get the bId to get the same generated value as aId? Note that afterwards, I want to be able to update bId from my gui. If the solution is JPA, even better.

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  • Log4j - Logging to multiple log files based on the project modules

    - by Veera
    Consider this scenario: I have a project with two modules and one common module as below (the package structure): com.mysite.moduleone com.mysite.moduletwo com.mysite.commonmodule In the above, the commonmodule classes can be used by other two modules. The question: I need to configureLog4J such a way that the log messages from moduleone and moduletwo goes to different log file. I can always do this using using category. But the real problem is when I want to log the messages from the commonmodule also. So, when the commonmodule classes are called from moduleone the commonmodule log messages should go to the moduleone log file. If the commonmodule is accesse from moduletwo the commonmodule log messages should go to moduletwo log file. Is it possible to configure Log4J in this fashion? Any comments? PS: I think I made my question clear. If any confusion, leave a comment, wil try to clear it. :)

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  • Invoke Maven-Module build from intellij

    - by Roman
    Hi All I was wondering if someone knows a way to invoke a specific maven module build from IntelliJ that will also build ( or use already compiled classes ) from depended modules. So for instance if I would like to build the module "Model" in the picture and only it , it seems reasonable for me to click the package step on it. But what is actually does it invokes the mvn package step inside this specific module rather than "mvn -am -pl module-name" from the root module , which also builds all the dependencies. So is there something that I just don't know ?

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  • select and jstl query

    - by sarah
    Hi All, I am displaying data in combo box using ${role} the requirement is on clcik of edit i want to show the preselected value in the drop down ,suppose i have cat,rat and i selected rat and i saved it in database ,now when i want to edit the details i want to show rat first in drop down as pre selected and then cat,how to od this ?

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  • Total row count for pagination using JPA Criteria API

    - by ThinkFloyd
    I am implementing "Advanced Search" kind of functionality for an Entity in my system such that user can search that entity using multiple conditions(eq,ne,gt,lt,like etc) on attributes of this entity. I am using JPA's Criteria API to dynamically generate the Criteria query and then using setFirstResult() & setMaxResults() to support pagination. All was fine till this point but now I want to show total number of results on results grid but I did not see a straight forward way to get total count of Criteria query. This is how my code looks like: CriteriaBuilder builder = em.getCriteriaBuilder(); CriteriaQuery<Brand> cQuery = builder.createQuery(Brand.class); Root<Brand> from = cQuery.from(Brand.class); CriteriaQuery<Brand> select = cQuery.select(from); . . //Created many predicates and added to **Predicate[] pArray** . . select.where(pArray); // Added orderBy clause TypedQuery typedQuery = em.createQuery(select); typedQuery.setFirstResult(startIndex); typedQuery.setMaxResults(pageSize); List resultList = typedQuery.getResultList(); My result set could be big so I don't want to load my entities for count query, so tell me efficient way to get total count like rowCount() method on Criteria (I think its there in Hibernate's Criteria).

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  • how to add hindi language support to struts webapplication.

    - by Vipin Nemade
    Hi, I am creating Web application using the struts 1.2. On which I have to add the Hindi language support to my Web application.I have created the Application_hi.properties file in which I have key equal to Hindi word. But it is giving the error like "some character cannot be map using ISO-8859-1 character encoding". thanks in advance................

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  • mig layout - span and grow/push problem

    - by pstanton
    i want 3 components laid out on 2 lines, so that the bottom component and the top-right component use all available horizontal space. JFrame frame = new JFrame(); frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); frame.setLayout(new MigLayout("debug, fill")); Container cp = frame.getContentPane(); cp.add(new JTextField("component 1"), ""); cp.add(new JTextField("component 2"), "growx,push,wrap"); cp.add(new JTextField("component 3"), "span,growx,push"); frame.pack(); frame.setVisible(true); considering the above, how do i stop the space between "component 1" and "component 2" from appearing when resizing the frame? thanks.

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  • @NamedQuery select parameter meaning

    - by sergionni
    Found some examples of @NamedQuery annotations,e.g.: @NamedQuery(name="employeeBySsn" query="select e from Employee e where e.ssn = :ssn") what does parameter e mean? the second usage of it seems like alias name of table and what does "select e" part mean?

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  • Unique task queue task names only for active duration

    - by antony.trupe
    I want to guarantee that a task is not in a task queue more then once, so I generate a unique name based on it's payload. But, that task name is reserved for up to 7 days, which is not what I want; I only want it reserved for the duration the task is queued; it could be immediately re-queued. Once a Task with name N is written, any subsequent attempts to insert a Task named N will fail. Eventually (at least seven days after the task successfully executes), the task will be deleted and the name N can be reused. Is there a way to check if the named task is already in the queue then add it if it's not? Or a totally different approach?

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  • Timer Service in ejb 3.1 - schedule calling timeout problem

    - by Greg
    Hi Guys, I have created simple example with @Singleton, @Schedule and @Timeout annotations to try if they would solve my problem. The scenario is this: EJB calls 'check' function every 5 secconds, and if certain conditions are met it will create single action timer that would invoke some long running process in asynchronous fashion. (it's sort of queue implementation type of thing). It then continues to check, but as long as long running process is there it won't start another one. Below is the code I came up with, but this solution does not work, because it looks like asynchronous call I'm making is in fact blocking my @Schedule method. @Singleton @Startup public class GenerationQueue { private Logger logger = Logger.getLogger(GenerationQueue.class.getName()); private List<String> queue = new ArrayList<String>(); private boolean available = true; @Resource TimerService timerService; @Schedule(persistent=true, minute="*", second="*/5", hour="*") public void checkQueueState() { logger.log(Level.INFO,"Queue state check: "+available+" size: "+queue.size()+", "+new Date()); if (available) { timerService.createSingleActionTimer(new Date(), new TimerConfig(null, false)); } } @Timeout private void generateReport(Timer timer) { logger.info("!!--timeout invoked here "+new Date()); available = false; try { Thread.sleep(1000*60*2); // something that lasts for a bit } catch (Exception e) {} available = true; logger.info("New report generation complete"); } What am I missing here or should I try different aproach? Any ideas most welcome :) Testing with Glassfish 3.0.1 latest build - forgot to mention

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  • Best way to detect duplicates when using Spring Hibernate Template

    - by Dean Povey
    We have an application which needs to detect duplicates in certain fields on create. We are using Hibernate as our persistence layer and using Spring's HibernateTemplate. My question is whether it is better to do so an upfront lookup for the item before creating, or to attempt to catch the DataIntegrityViolation exception and then check if this is caused by a duplicate entry.

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  • What is viewstate in JSF, and how is it used?

    - by MatthieuF
    In JSF, there is a viewstate associated with each page, which is passed back and forth with submits etc. I know that viewstate is calculated using the states of the various controls on the page, and that you can store it either client side or server side. The question is: how is this value used? Is it used to validate the values sent at submit, to ensure that the same request is not sent twice? Also, how is it calculated - I realise that richfaces may be calculated differently from myfaces, but an idea would be nice. Thanks.

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  • Return value changed after finally

    - by Nestor
    I have the following code: public bool ProcessData(String data) { try { result= CheckData(data); if (TextUtils.isEmpty(result)) { summary="Data is invalid"; return false; } ... finally { Period period = new Period(startTime, new LocalDateTime()); String duration = String.format("Duration: %s:%s", period.getMinutes(), period.getSeconds()); LogCat(duration); } return true; As I learned from this question, the finally block is executed after the return statement. So I modified my code according to that, and in the finally I inserted code that does not modify the output. Strangely, the code OUTSIDE the finally block does. My method always returns true. As suggested, it is not a good idea to have 2 return. What should I do?

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  • How to use pom.xml/Maven to initialize a local thoughtsite (App Engine sample) project in Eclipse?

    - by ovr
    This sample app ("thoughtsite") for App Engine contains a pom.xml in its trunk: http://code.google.com/p/thoughtsite/source/browse/#svn/trunk But I don't know what command to run in Maven to set up the project locally. (The README doesn't mention anything about Maven.) I tried to just import the project code directly into Eclipse but it doesn't look like it's in an appropriate format for a direct import. So I assume I need to do something with Maven to get it set up correctly. I haven't really used Maven before so I'm not sure what command I would need to run to set everything up. The pom.xml seems like it downloads a bunch of dependencies for the project like the Spring jar files which I don't see anywhere else in the svn repository.

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